Very small movements between an implant and the bone can be measured by special RSA X-rays after implantation of small (0.8-1.0 mm) Tantalum markers attached to the implant and in the bone (Selvik 1989), while changes in bone mineral or bone mineral density (BMD) of the bone in close relation to the implant can be measured by DEXA (Glüer et al. 1990, Mazess & Barden 1988).